Technical Field
The present invention relates to a synchronization method and a signal processing system using the method. More particularly, the present invention relates to a touch signal synchronization method and a touch signal processing system using the method.
Description of Related Art
Along with the development of technology, the needs for more efficiently processing data or signals are more demanded. Under such development trend, the processing power of one single integrated circuit has no longer sufficient. Therefore, it is natural that multiple-IC solutions are getting more and more attention. By utilizing multiple-IC, for example using multiple microprocessors, multiple digital signal processors in a signal processing system, the processing power and multi-task ability of the system can be greatly increased. However, under the high-speed, high-frequency operating conditions, the signal synchronization rate between different integrated circuits are getting more and more important.
In one example, in a signal processing system that is used for processing touch signals, when a single IC is used to drive multiple analog-to-digital converters (ADCs) to conduct touch signal detection, these ADCs are receiving signals from the same processing core (i.e. the single IC), there will normally be no synchronization defects among these ADCs. Due to the reason that the electronic devices are now having higher and higher standards for processing touch signals, like growing touch point numbers, rising refreshing rates, or increasing touch accuracy, multiple ICs are used in an attempt to collaborate with multiple high speed, high frequency ADCs. When different ADCs are receiving signals from different ICs correspondingly, the inconsistency between any two ADCs in signal synchronization will lead to failure of hopping frequency measurement. The hopping frequency measurement is used to avoid noises from affecting touch signals. In the case of failure hopping frequency measurement, the touch accuracy will be affected accordingly.
Generally, during synchronization between different ICs, a slave IC is selected to do polling with program codes to frequently read signals from the master IC. The synchronization will not start until the signal from the master IC is picked up by the slave IC. The synchronization rate related to software program codes will be affected by the length of the codes, thus the system has the chance of incurring a temporal error whose duration is equal to one or more NOPs (no-operation-perform, NOP). The temporal error normally includes 1-4 NOPs (depending on the length of the codes) and can be regarded as an unexpected time differentiation between the slave IC and the master IC. Consequently, the effect of the hopping frequency measurement is diminished, and the efficiency of filtering out the noise is decreased. Further, the touch control accuracy of the system is affected accordingly.